1. Field of the Invention
The present invention relates to a servo control method for a hard disk drive (hereinafter, referred to as an HDD) and, in particular, to a servo control method for a high capacity hard disk drive.
2. Description of the Related Art
Conventionally, an HDD, which is widely used as an auxiliary memory of a computer system, is generally constructed with a read/write channel for reading data stored on a disk and for converting the read data, i.e., converting an analog signal into a digital signal, a microprocessor for communicating with a host computer and for performing an overall control operation of the HDD system, and a servo controller for moving a head to a specific position on the disk. Using a servo control, the HDD constructed as described above operates in a track seek mode and a track following mode in accordance with a moving distance of an actuator. The track seek mode moves the actuator to a target track and the track following mode controls the head of the actuator while placed on the target track so that the head lies on-track. In the conventional HDD, velocity control of the actuator is effected in the track seek mode, and position control is effected in the track following mode. The disk used as a recording medium of the HDD is divided into a number of tracks where a servo sector and a data sector are alternately arranged such that about 9.about.10% of the entire capacity of the disk is utilized as the servo sector.
Typically, the track for each head on a platter in a hard disk drive using a multiple platter arrangement includes a data sector having ID field and a data field, and a servo sector consisting of a preamble, a servo address mark, a gray code field for providing the information for each track number, and a plurality of servo bursts for providing position error signals required for operation of the track seek mode and the track following mode. Lastly, a PAD field is provided to give a transition margin from the servo sector to the data sector. Each of the patents to Hetzler, U.S. Pat. No. 5,523,903, BANDED MAGNETIC RECORDING DISK WITH EQUALLY-ANGULARLY-SPACED SERVO SECTOR, Hetzler, et al., U.S. Pat. No. 5,526,211, SECTOR ARCHITECTURE FOR FIXED BLOCK DISK DRIVE, Machado, et al., U.S. Pat. No. 5,418,657, TRACK ADDRESS DETECTING MEANS BY HDD SECTOR SERVO METHOD, and Chiao, et al., U.S. Pat. No. 5,515,212, VERY-HIGH DENSITY DISKETTE FORMAT METHOD AND COMPUTER IMPLEMENTED PROCESS, discloses prior art disk drive arrangements having formats similar to those noted above.
None of the cited art has been able to reduce the size of the servo sector by eliminating the gray code field from some of the servo sectors in each track as in the present invention so as to increase the density on the hard disk drive as in the present application.